--- title: "Headless CMS FAQs" description: "Headless CMS FAQs" url: "https://www.contentstack.com/docs/headless-cms/faqs" product: "Contentstack" doc_type: "guide" audience: - developers - admins version: "current" last_updated: "2026-04-21" --- # Headless CMS FAQs ## Access Token Removal FAQs ### What is Access Token removal? Access Token removal refers to the deprecation of Access Tokens in Contentstack for [stacks](/docs/developers/set-up-stack/about-stack) created after **December 16, 2020.** Thus, new stacks no longer support Access Tokens for authentication. Instead, you can: * Use [Delivery Tokens](/docs/developers/create-tokens/about-delivery-tokens/) with the access\_token header for [Content Delivery API](/docs/developers/apis/content-delivery-api) requests. * Use [Management Tokens](/docs/developers/create-tokens/about-management-tokens/) or [Authtokens](https://www.contentstack.com/docs/developers/create-tokens/types-of-tokens#authentication-tokens-auth-tokens) for [Content Management API](/docs/developers/apis/content-management-api/) requests. This enhances security and provides more control over content access. ### Why were Access Tokens deprecated? Access Tokens provided broad stack-level access, including both published and draft content across [environments](/docs/developers/set-up-environments/about-environments), which increased security risks. To enhance security and improve management flexibility, Contentstack introduced [Delivery Tokens](/docs/developers/create-tokens/about-delivery-tokens/) and [Management Tokens](/docs/developers/create-tokens/about-management-tokens/) as more secure alternatives. ### Is there a way to reset my existing Access Token? Yes. The stack [Owner](/docs/developers/invite-users-and-assign-roles/types-of-roles#owner), [Admin](/docs/developers/invite-users-and-assign-roles/types-of-roles#admin), or [Developer](/docs/developers/invite-users-and-assign-roles/types-of-roles#developer) can reset the Access Token for stacks created before **December 16, 2020.** ### What tokens should I use instead of the Access Token? * Use Delivery Tokens to fetch environment-specific published content such as [assets](/docs/content-managers/author-content/about-assets) and [entries](/docs/content-managers/author-content/about-entries) via the Content Delivery API. * Use Management Tokens or Authtokens to fetch unpublished or draft content via the Content Management API. ### Does Access Token deprecation affect all stacks? No. The deprecation only applies to stacks created after **December 16, 2020**. [Stacks](/docs/developers/set-up-stack/about-stack) created before this date still support Access Tokens. However, using Delivery and Management Tokens is strongly recommended. ### Can I view unpublished or draft content without the Access Token? Yes. You can use a Management Token or your user-specific Authtoken to fetch unpublished or draft content. ### Give me an example request that no longer works since Access Token support ended? The following example request uses an Access Token: \# Making a GET request to retrieve a specific entry from a given content type. curl -X GET \\ 'https://api.contentstack.io/v3/content\_types/{ContentTypeUid}/entries/{EntryUid}?include\_publish\_details=true&include\_workflow=true' \\ \-H 'accept-encoding: application/json' \\ # Ensures JSON response \-H 'access\_token: {your\_access\_token}' \\ # Authorization token for the API \-H 'api\_key: {your\_api\_key}' # API key identifying the stack This request **does not** work for stacks created after **December 16, 2020**. Replace {your\_access\_token} with your Delivery Token. ### How do I replace Access Tokens with Delivery or Management Tokens? To replace Access Tokens with Delivery Tokens: 1. [Generate a separate Delivery Token](/docs/developers/create-tokens/create-a-delivery-token) for each publishing environment. 2. Use the Delivery Token value in the access\_token header for Content Delivery API calls. To replace Access Tokens with Management Tokens: 1. Generate a Management Token or request one from the stack [Owner](/docs/developers/invite-users-and-assign-roles/types-of-roles#owner) / [Admin](/docs/developers/invite-users-and-assign-roles/types-of-roles#admin). 2. Use the Management Token value in the authorization header for Content Management API calls. ### How can I replace the Access Token in my existing scripts? For **published content** (Content Delivery API): Use a Delivery Token in the access\_token header. `-H 'access_token: {delivery_token}'` For unpublished content (Content Management API): Use a Management Token in the authorization header. `-H 'authorization: {management_token}'` ### Can I see when my Access Token was last used? No. Contentstack does not log Access Token usage. You must manually replace Access Tokens with Delivery or Management Tokens in your scripts and integrations. ### Why am I still seeing the access_token key in headers after deprecation? The access\_token key remains valid for older stacks (before December 16, 2020). New stacks must use **Delivery Tokens** in this header. For newer stacks, use the Delivery Token value in the access\_token header. ### Is there a quick reference guide to understand tokens in Contentstack? You can refer to the [Types of Tokens](/docs/developers/create-tokens/types-of-tokens) document to understand the differences, usage, and limitations. ### Can I use a Management Token with the access_token parameter? No. Use: * **Delivery Tokens** with the access\_token header (Content Delivery API) * **Management Tokens** with the authorization header (Content Management API) ## Architecture FAQs ### What is a partially headless setup, and when do I need one? What does a fully headless setup look like? Partially headless setup means you have some portion of your website on a traditional setup and the remaining on a headless CMS. This setup is useful in cases when migrating from a conventional CMS to a headless CMS. The [partially headless architecture](/docs/developers/architecture-diagrams/partially-headless-setup-detailed-architecture) diagram shows how one content section, such as blog, is migrated to a headless CMS, whereas the rest of the digital properties remain on a traditional setup. ### What do we consider a simple site? A simple site is a website that has a few pages and limited third-party integration. An example of a [simple website](/docs/developers/architecture-diagrams/simple-website-detailed-architecture) could be a marketing site of an enterprise, which uses basic integration services such as website search, site analytics, and so on. ### How do I know if I should set up a static site or a simple site? If the sole purpose of your website is to serve content, and is likely to deliver the same content to all users, you must go for a static website. [Dynamic](/docs/developers/architecture-diagrams/dynamic-website-detailed-architecture) or [simple website](/docs/developers/architecture-diagrams/simple-website-detailed-architecture) architecture, on the other hand, integrates well with other apps, helps you do more with content (such as deliver personalized content, etc.) and enables user interaction. ### Can I start simple and move to a dynamic setup? Yes. In such a case, it is recommended to use the complex website architecture as it offers the required flexibility and agility to add more services. So initially, if your website is simple but gradually develops to become complex, use the complex website architecture for effective scaling. ### Which setup scales the best? The [dynamic website](/docs/developers/architecture-diagrams/dynamic-website-detailed-architecture) architecture provides better flexibility and agility. You can add more services as required, without impacting or changing any other components, enabling quick scaling. ## Stack Assets FAQs ### What types of media files are supported? Contentstack supports various media file types, including image links, video links, GIFs, and more. These files can be uploaded as [assets](/docs/content-managers/working-with-assets/about-assets) and used in [entries](/docs/content-managers/working-with-entries/about-entries). ### What is the maximum allowed size of a single asset (file) that can be uploaded? The maximum allowed size for a single asset file is **700 MB**. Additionally, you can define custom file size limits (both maximum and minimum) using the [File Size Limit](/docs/developers/how-to-guides/validations#file-size-limit) validation rule. ### Is there a limit to the total number of assets that can be uploaded in a stack? Yes. A maximum of **10,000 assets** can be uploaded in a stack. The limit can be increased based on your plan. Contact our [support](mailto:support@contentstack.com) team for more details. ### How to use Image Delivery API requests on images inserted directly into the Rich Text Editor (RTE)? Contentstack does not support applying [Image Delivery API](/docs/developers/apis/image-delivery-api/) requests on images directly inserted into text fields. However, you can achieve this by following these steps: 1. **Upload the Image as an Asset**: Upload the image to the Asset module using the [Upload Asset](/docs/developers/apis/content-management-api#upload-asset) API call. The response body will include the url parameter containing the asset’s URL and a unique uid for the uploaded asset. 2. **Insert the URL into the Text Field**: In the **Rich Text Editor** (**RTE**) or any other text field, switch to the HTML code view and use the asset URL as the image source instead of directly inserting the image. 3. **Use the Image Delivery API**: With the asset’s UID and URL, you can apply Image Delivery API requests to modify the image as needed. ### Is it possible to query the same asset with different dimensions? Yes, you can use the [Image Delivery API](/docs/developers/apis/image-delivery-api/) to query the same asset with different dimensions. ### Is it possible to edit assets in bulk? No, bulk editing of assets is not supported. You can edit only one asset at a time. For more details, refer to the available [bulk operations on assets](/docs/content-managers/author-content#bulk-operations-on-assets). ### Does Contentstack support additional metadata for assets and entries? Yes, the additional metadata support for assets/entries is available. ### Does the version of an asset or entry change when additional metadata is added using the API? No, adding metadata via the API does not increment the version of the entry or asset. ### If I publish an asset or entry, will its metadata also be published? When you publish an entry or asset, its associated metadata is also published. However, for bulk publishing of entries or assets, the metadata is not published. For more information, refer to the [publish metadata](/docs/developers/apis/content-management-api#publish-metadata) documentation. ### How can I add additional metadata to an asset or entry? You can add additional metadata to an asset or entry only through the [Metadata for Entries and Assets](/docs/developers/apis/content-management-api#metadata-for-entries-and-assets) Content Management API requests. ### What is the maximum metadata size limit for an entry or asset? The maximum metadata size allowed per extension is **5 KB**. This includes the total metadata defined for all entries and assets associated with the extension. ### What happens to an asset's URL if it is unpublished? When an asset is unpublished, it becomes inaccessible in the environments and locales it was unpublished from. However, the URL remains active and accessible within the Contentstack assets repository unless the asset is deleted. ### Can I customize the asset filename after uploading it? No, once an asset is uploaded, the filename cannot be changed. ### Does replacing an asset affect its references in entries? Replacing an asset does not break references in entries as long as you are using [permanent URLs](/docs/content-managers/author-content/generate-a-permanent-asset-url/). ### Can I organize assets into folders or categories? Yes, Contentstack allows you to organize assets into [folders](/docs/content-managers/author-content/create-a-folder) for easier management. You can create nested folders and move assets between them. ### Is it possible to restore a deleted asset? [Trash](/docs/developers/manage-trash/about-trash) maintains a backup of all deleted assets for up to **14 days** from the date of deletion. You can [restore](/docs/developers/manage-trash/restore-a-deleted-asset) deleted assets before they are permanently deleted. ### Does Contentstack support asset versioning? Yes, Contentstack maintains a [version history](/docs/content-managers/author-content/about-asset-versioning) for assets, allowing you to view and restore previous versions if necessary. ## Asset Folder-level Permission FAQs ### What is the primary purpose of asset folder-level permissions? [Asset folder-level permissions](/docs/developers/invite-users-and-assign-roles/create-a-role#permissions-on-assets/) define specific actions a custom user role can perform on an asset folder. This ensures that users only interact with the folders and assets they are authorized to access, providing enhanced control over content management. ### Can I assign permissions to multiple asset folders at once? Yes, you can select multiple asset folders and assign them to a custom role simultaneously. This streamlines the process of managing [permissions](/docs/developers/invite-users-and-assign-roles/create-a-role#permissions-on-assets/) across multiple folders. ### Can I assign different permissions to different asset folders? Yes, you can assign distinct [permissions](/docs/developers/invite-users-and-assign-roles/create-a-role#permissions-on-assets/) to different asset folders. For example, you could grant “Read” permission to one folder (e.g., Folder 1) and “Publish” permission to another (e.g., Folder 2), depending on your organizational needs. ### Do folder-level permissions apply to the assets and subfolders within a folder? Yes, when you assign [permissions](/docs/developers/invite-users-and-assign-roles/create-a-role#permissions-on-assets/) to a folder, those permissions also apply to its assets and any subfolders, ensuring consistent access control within the folder hierarchy. ### Can I revoke folder-level permissions from a custom role? Yes, you can modify or revoke [permissions](/docs/developers/invite-users-and-assign-roles/create-a-role#permissions-on-assets/) for a custom role at any time. This change will immediately take effect, updating the role's access to the folder, its assets, and its subfolders. ### What happens if a user belongs to multiple roles with different permissions? When a user belongs to multiple roles with varying [permissions](/docs/developers/invite-users-and-assign-roles/create-a-role#permissions-on-assets/): * **Permissive actions are merged**: If one role grants "Update" permission and another grants "Publish," the user will have both permissions. * **Cannot Do permissions take precedence**: If one role allows "Read" and another explicitly denies "Read," the restriction takes priority, and the user’s access is limited. This ensures that restrictive permissions are prioritized for better control and security. ## Branches FAQs ### How does this feature affect the other modules in Contentstack? The modules currently available in Contentstack will not be affected. Some modules are branch-specific. Whereas some are globally available throughout all the branches. You will have an additional scope section where you can decide whether you want that module for either all or specific branches for which you want the module. Please refer to our [Branch-Specific Modules](/docs/developers/branches/branch-specific-modules) and [Global Modules](/docs/developers/branches/global-modules) documentation for more information. ### What are branch-specific modules? Modules such as [Content Types](/docs/developers/create-content-types/about-content-types), [Global Fields](/docs/developers/global-field/about-global-field), [Entries](/docs/content-managers/working-with-entries/about-entries), [Assets](/docs/content-managers/working-with-assets/about-assets), [Publish Queue](/docs/content-managers/publish-content/view-publish-status-of-entries-assets-in-publish-queue), [Releases](/docs/developers/create-releases/about-releases), [Languages](/docs/developers/multilingual-content/about-languages), [Extensions](/docs/developers/about-experience-extensions), [Audit Logs](/docs/developers/set-up-stack/monitor-stack-activities-in-audit-log), [Global search](/docs/developers/branches/branch-specific-modules/#global-search), and [Labels](/docs/developers/create-content-types/about-labels) are branch specific. They can be created, updated, or deleted within a particular branch without affecting any other branch. Their details can differ across the other branches present in a stack. Please refer to our [Branch-Specific module](/docs/developers/branches/branch-specific-modules) documentation for more information. ### What are global modules? Modules such as [Environments](/docs/developers/set-up-environments/about-environments), [Webhooks](/docs/developers/set-up-webhooks/about-webhooks), [Workflows](/docs/developers/set-up-workflows-and-publish-rules/about-workflows), [Publish Rules](/docs/developers/set-up-workflows-and-publish-rules/about-publish-rules), [Users](/docs/developers/invite-users-and-assign-roles/about-stack-users), [Roles,](/docs/developers/invite-users-and-assign-roles/about-stack-roles) and [Tokens](/docs/developers/create-tokens/types-of-tokens) are globally available. Details for these modules are available across every branch of the stack. Please refer to our [Global Modules](/docs/developers/branches/global-modules) documentation for more information. ### Which Roles can access the branches feature? Any user with the role “[Owner,](/docs/developers/invite-users-and-assign-roles/types-of-roles/#owner)” “[Admin,](/docs/developers/invite-users-and-assign-roles/types-of-roles/#admin)” and “[Developer](/docs/developers/invite-users-and-assign-roles/types-of-roles/#developer)” will be able to use the branches feature. [Content managers](/docs/developers/invite-users-and-assign-roles/types-of-roles/#content-manager) can only work within the branches assigned to them. [Custom roles](/docs/developers/invite-users-and-assign-roles/types-of-roles/#custom-role) can access branches as per the permissions assigned to them. ### Can we set up a webhook or workflow for a specific branch? Yes. You can set up a webhook or workflow for a specific branch. The system allows the creation of [branch-specific](https://www.contentstack.com/docs/developers/branches/branch-specific-modules) workflows for a content type. ### Can I add languages specific to a branch? Yes, you can add languages only to a specific branch of the stack. That language will not be available in other branches of the stack. Please refer to the [Languages](/docs/developers/branches/branch-specific-modules/#languages) section in our [Branch-specific Modules](/docs/developers/branches/branch-specific-modules/) document for more information. ### How do I work with Extensions within branches? Extensions are specific to a branch. If you add an extension within a branch, it won’t be available across other branches. Please refer to the [Extensions](/docs/developers/branches/branch-specific-modules/#extensions) section in our [Branch-specific Modules](/docs/developers/branches/branch-specific-modules/) document for more information. ### Can I delete the main branch? No, the main branch cannot be deleted. Please refer to the [Limitations of Branches](/docs/developers/branches/limitations-of-branches) document. ### Can two different aliases point to the same branch? Yes, two different aliases can point to the same branch. Learn how to [Assign an Alias to a Branch](/docs/developers/branches/assign-an-alias-to-a-branch). ### Can a branch and an alias have the same unique ID? No, you cannot have the same unique ID for a branch and an alias. ### How do I work with branches using Content Management API? You can retrieve information from all or a specific branch. You can also create and delete a branch using the API requests. You will need to pass the branch header if you want to execute calls within specific branches. Please refer to the [Branches](/docs/developers/apis/content-management-api#branches) collection in our Content Management API documentation for more information. ### What changes are expected in the existing Content Management API requests? You can add a branch header while executing an API request to get details specific to a branch. If this header is not mentioned, by default, data will be retrieved from the "main" branch of your stack. The response body for every request will contain the \_branch parameter specifying the branch from which the information is retrieved. Please refer to our [Content Management API](/docs/developers/apis/content-management-api) documentation for more information. You can also visit the [API Change Log](/docs/developers/apis/api-change-log/february-25-2022) for more details about the breaking changes. ### How can I compare branches? You can compare two branches to get the differences in the content type or global field modules, by either using the [Comparing Branches](/docs/developers/apis/content-management-api/#branches) requests in [Content Management API](/docs/developers/apis/content-management-api/) or the [Compare Branches using the CLI.](/docs/developers/cli/compare-and-merge-branches-using-the-cli/#steps-to-compare-branches) ### How can I merge branches? You can merge the differences in the content type or global field modules of two branches, by either using the [Merging Branches](/docs/developers/apis/content-management-api/#merging-branches) requests in [Content Management API](/docs/developers/apis/content-management-api/#branches) or the [Branch Merge using the CLI.](/docs/developers/cli/compare-and-merge-branches-using-the-cli/#steps-to-merge-branches) ### Is the compare and merge feature available for all the modules in a branch? No, currently the compare and merge feature is only available for the content type and global field modules. ### Can I compare and merge branches via the CMS? No, currently the compare and merge feature is only available via [CMA requests](/docs/developers/apis/content-management-api/#comparing-branches) or [CLI commands.](/docs/developers/cli/compare-and-merge-branches-using-the-cli/) ### How many branches can I compare or merge at once? You can compare or merge two branches at a time. Please refer to our documentation on [Comparing and Merging Branches](/docs/developers/branches/about-compare-and-merge-branches/) for more information. ### Are there different strategies for merging two branches? Yes, there are various merge strategies to choose from while merging two branches. Please refer to our [Merging Branches](/docs/developers/branches/merging-branches) documentation for more information on how to select the best possible merge strategy. ### What if my merge action fails? Before performing a merge, pre-checks are performed to make sure the merge can complete. If these pre-checks fail, the merge will not be attempted, and you’ll see that merge job as failed, with an explanation of why. If these checks pass, the merge will be performed. By default, a backup branch is created of the branch you are merging into before any merge action takes place. You can create and point an alias to this backup branch to get your production website back to it’s previous state. Please refer to our [Merging Branches](/docs/developers/branches/merging-branches) documentation for more information on how to select the best possible merge strategy. ## CLI FAQs ### How can I use the Europe, Azure North America, Azure Europe, or Google North America endpoint to execute CLI commands? Use the Set Region command to set up and use the Europe, Azure North America, Azure Europe, or Google North America region. ### Does the “Delete Token” command delete the token from the stack? No. The [Delete Token](/docs/developers/cli/cli-authentication#delete-token) command removes the token only from the current session and not from the stack. ### Can I clone stacks using CLI? Yes. Refer to the Clone a Stack guide to get started. ### How does the export and import command work? You can use the [export](/docs/developers/cli/export-content-using-the-cli) and [import](/docs/developers/cli/import-content-using-the-cli) commands to migrate your content from one stack to another. To do this, first you need to use the export command to export the content from the source stack and then use the import command to import it into the destination stack. ### How to export content into a .CSV file? You can use the **cm:export-to-csv** CLI command to export stack data into a CSV file. For more details refer our detailed [guide](/docs/developers/cli/export-content-to-csv-file) on the topic. ### What is the Bootstrap Starter Apps command? The Bootstrap Starter Apps command automates the procedure of stack creation and setting up the project (starter app). Follow [this](/docs/developers/cli/bootstrap-starter-apps) guide to set up and run a starter app with minimal steps. ### Can I merge branches using the CLI migration command? No. Currently, the **branches** **merge feature** is **not supported**. ## Content Type FAQs ### Can I add custom fields to a content type? Yes. You can create and add custom fields to your content type. To learn more, refer to the [Custom Fields](/docs/developers/create-custom-fields/about-custom-fields) documentation. ### Is there a limit to the number of fields in a content type? Yes. A content type can have up to **500 fields**. ### Can I remove the default “Title” field from a content type? No. The [Title](/docs/developers/create-content-types/title) field is a default field and cannot be removed. ### Can the “Title” field be set as non-unique? No. The **Title** field is always unique by default. ### How do references work in content types? The [Reference](/docs/developers/create-content-types/reference) field allows you to include entries from other content types within a content type. ### How do I change the display name of a field? When you [create a content type](/docs/developers/create-content-types/create-a-content-type) and add a field, follow these steps to change its display name: 1. Click the “Properties” (gear) icon for the field. 2. Enter a suitable title under the [Display Name](/docs/developers/create-content-types/display-name) property. ### Can I add tooltips to fields? Yes. You can add tooltips using the [Help Text](/docs/developers/create-content-types/help-text) property of a field. 1. Click the “Properties” (gear) icon for the field. 2. In the **Help Text** field, enter the text you want to display as a tooltip. 3. Hyperlinks are supported. **Tip**: Keep tooltips short and precise. ### Can I change the UID of a content type? No. Once created, a content type’s UID cannot be changed. However, you can edit the UID while [creating the content type](/docs/developers/create-content-types/create-a-content-type). ### Why do I get an error when changing a field UID to camelCase? Field UIDs must contain only lowercase characters (a–z) and numbers (0–9). Uppercase letters are not allowed. ### Why do I get the error “Schema.3.uid is a restricted value”? This error occurs when a field UID uses a reserved keyword. Contentstack [restricts certain keywords](/docs/developers/create-content-types/restricted-keywords-for-uids) from being used as UIDs in content types or entries. ### Can I revert to a previous version of a content type via the UI? No. Contentstack lets you [compare content type versions](/docs/developers/create-content-types/content-type-versioning), but you cannot revert to an earlier schema version. ### How do I restore a previous version of a content type? You can restore a content type using APIs: 1. Fetch the previous version of the content type using the [Versioning API](/docs/developers/apis/content-management-api#get-a-single-content-type). 2. Use the [Import a Content Type API](/docs/developers/apis/content-management-api#import-content-type) to import the version you fetched. **Warning**: Restoring a previous version saves it as a new version, which may lead to data loss. ### Can I compare non-sequential versions? Yes. The **Compare Versions** screen lets you select any two saved versions of a content type, even if they are not consecutive. ### Does field reordering appear in comparisons? No. Field reordering is not tracked in content type version comparisons because it does not affect the underlying data. ### Does versioning affect entries or only schemas? Versioning applies only to the **content type schema**. Entry data, workflow states, and published content remain unaffected. ### Can I restore or copy fields from an older version? No. You cannot directly restore fields from a previous version, but you can manually recreate them using the comparison view as a reference. ### How are schema changes highlighted in comparisons? Contentstack uses **Added**, **Deleted**, and **Modified** tags to indicate schema changes between versions. ### Are version numbers editable? No. Contentstack automatically assigns sequential version numbers, which cannot be renamed or manually managed. ### Is there a limit to the number of versions stored? No. All saved versions of a content type are retained, although performance may be affected if an unusually large number of versions is stored. ### Do you provide sample content type templates? Yes. Contentstack provides: * [Starter apps](/docs/developers/sample-apps/) that include ready-made content type templates (JSON files). You can import these JSON files into your stack to get started. * [Prebuilt content models](/docs/developers/create-content-types/import-prebuilt-content-models/) that you can use directly to speed up your setup. ### What are the best practices for changing a content type schema? Refer to the [Best Practices for Content Type Changes](/docs/developers/how-to-guides/content-type-change-management) guide. It covers scenarios to help you avoid data loss when making schema changes. ### Is there a character limit for key-value pairs in Select fields? Yes. Each key and value can contain up to **100 characters**. ### Will the JSON schema change for Select fields with key-value pairs? Yes. The JSON schema for Select fields includes both key and value data. Refer to the [Select Field Schema](/docs/developers/create-content-types/json-schema-for-creating-a-content-type#select) documentation for details. ### Will choices be deleted if I toggle the Enable key-value option in Select fields? Yes. All existing choices are lost if you toggle this option. ### Can I migrate content from HTML RTE to JSON RTE? Yes. You can migrate content using CLI. Refer to the [JSON RTE Migration](/docs/developers/cli/migrate-content-from-html-rte-to-json-rte/) Guide. ### Can I migrate HTML RTE to JSON RTE in bulk? Yes. You can migrate all entries in a content type from HTML RTE fields to JSON RTE fields in just a few minutes. Refer to the [JSON RTE Migration](/docs/developers/cli/migrate-content-from-html-rte-to-json-rte/) guide. ### How do I add HTML tags in JSON RTE? In the formatting bar, click **Property** > **Add Properties**, enter the details in the modal that appears, and click **Apply**. ### Can I get an HTML response from JSON RTE? Yes. Add the include\_html parameter when fetching an entry. For examples, refer to the following API requests: * [Create a content type with JSON RTE](/docs/developers/apis/content-management-api#create-content-type-with-json-rte) * [Create an entry with JSON RTE](/docs/developers/apis/content-management-api#create-an-entry-with-json-rte) * [Update an entry with JSON RTE](/docs/developers/apis/content-management-api#update-an-entry-with-json-rte) ## Contentstack FAQs ### What is Contentstack? Contentstack is a headless CMS with an API-first approach that puts content at the center. It is designed to simplify the process of publication by separating code from content. You can access, create, and manage content in Contentstack, via RESTful APIs, across multiple channels such as websites, mobile apps, or any other platform. Go through our [Contentstack](https://www.contentstack.com/) website. ### How do I get started with Contentstack? You will first need a Contentstack account to get started. Once you have an account, read our docs to understand how Contentstack works. Developers who are well aware of Contentstack and are interested in creating websites and apps can get started with our docs on various [platforms](/docs/developers#development-resources). While new users, content managers, and editors can go through the basic concepts of creating a website or app in Contentstack [](/docs/content-managers)in our [Content Manager's Guide](/docs/content-managers). ### Is there a step-by-step tutorial to create a website/app from scratch? Yes, you can go through the [Platforms and SDKs](/docs/developers#platforms-and-sdks) section where you can find our step-by-step tutorial for creating a website or app in Contentstack for some of the common platforms, such as JavaScript, iOS, React Native, etc. You can also refer to the [Sample Apps](/docs/developers/sample-apps) for more step-by-step guides. ### What software do I need to get Contentstack running? Since Contentstack is a cloud-based CMS, you do not need anything (except for an internet connection, a browser, and a [Contentstack](https://www.contentstack.com/) account) to get started. ### What kind of support does Contentstack provide? Contentstack provides 24x7 online support. You can contact the support team either by using the in-product chatbox or by emailing us at [support@contentstack.com](mailto:support@contentstack.com). To learn more about Contentstack, visit [Contentstack Academy](https://www.contentstack.com/academy). ### Does Contentstack provide any kind of training? Contentstack does not provide any formal training. However, it provides extensive [documentation](/docs) that covers a wide range of topics including, important concepts, guides, tutorials, SDK and API references, code samples, and short videos that help you learn and get started with Contentstack. ### What hardware do I need to get Contentstack running? Contentstack is a cloud-based CMS. This means that you just need an internet connection on your desktop, laptop, or tablet to get started with Contentstack. ### What browsers do you support? Are there any system requirements for using Contentstack? Contentstack runs on all modern desktop browsers. ### Where does Contentstack store/save my data? Contentstack stores all of its data in MongoDB Server. ### Do I have to host my website with Contentstack? You are free to host your website with any provider of your choice. Alternatively, you can use Contentstack’s own front-end hosting and deployment platform, [Contentstack Launch](/docs/developers/launch/about-launch/), for websites built on the Contentstack CMS. ## Contentstack DataSync FAQs ### Are the Sync tokens and Data stored in encrypted formats? No, the Sync tokens and Data are stored in the Filesystem in a plain-text format. ### Can I store my data on other database systems? Yes, you can store your data on Filesystem, as well as on other database systems, such as MongoDB. ### Currently, I am running a website on contentstack-express. So, how can I switch from contentstack-express to DataSync? You can switch from contentstack-express to DataSync by following the steps mentioned in the [migration guide](/docs/developers/develop-apps-with-datasync/contentstack-datasync-vs-contentstack-express#migrate-from-contentstack-express-to-contentstack-datasync). ## Delivery Token FAQs ### ​What is the difference between Access Tokens and Delivery Tokens? Both Access Tokens and Delivery Tokens provide read-only access to a [stack](/docs/developers/set-up-stack/about-stack). * [Access Tokens](https://www.contentstack.com/docs/developers/create-tokens/types-of-tokens#access-tokens) can retrieve published and unpublished (draft) [entries](/docs/content-managers/author-content/about-entries), regardless of the environment. * Delivery Tokens can only retrieve published entries from the specific environment linked to the token.**Note:** Access Tokens are no longer supported for stacks created after December 16, 2020. Use Delivery Tokens for accessing published content and Management Tokens for Content Management API requests.**Additional Resource:** Refer to [Types of Tokens](/docs/developers/create-tokens/types-of-tokens) to learn more about different tokens available in Contentstack. ### Can I use Delivery Tokens to create content? No. **Delivery Tokens** are read-only and can only be used to retrieve published content. You cannot use them to create or update content. ### Can I use Delivery Tokens to fetch unpublished content? No. You can use Delivery Tokens only to fetch published content from the environment they are associated with. They cannot retrieve draft or unpublished content. ### Can I have a Preview Token without a Delivery Token? No. [Preview Tokens](/docs/developers/create-tokens/about-delivery-tokens#understanding-preview-tokens) are linked with Delivery Tokens. You must first [create a Delivery Token](/docs/developers/create-tokens/create-a-delivery-token) and [generate a Preview Token](https://www.contentstack.com/docs/developers/create-tokens/create-a-delivery-token#create-a-preview-token-for-an-existing-delivery-token). ### Can the same Delivery Token be used for both production and staging environments? No. A Delivery Token is strictly [environment](/docs/developers/set-up-environments/about-environments)\-specific. You must [create separate Delivery Tokens](/docs/developers/create-tokens/create-a-delivery-token) for each environment for clear data separation. ### Do I need Delivery Tokens if I'm already using Management Tokens? Yes. [Management Tokens](/docs/developers/create-tokens/about-management-tokens) provide full access to your [stack](/docs/developers/set-up-stack/about-stack), including unpublished content, and must remain private. Delivery Tokens offer read-only access to only the published content, making them suitable for use in public-facing applications. They help maintain better security and data boundaries. ### Who can create a Preview Token? Anyone with access to your stack's settings can generate a Preview Token. ## Drafts and Auto Save FAQs ### What Happens if I Close the Editor? [Drafts and Auto Save](/docs/content-managers/author-content/about-drafts-and-auto-save) automatically stores draft updates, so you do not need to manually click **Save** before leaving the editor. If you close the browser tab or refresh the page: * Your most recent synced changes remain saved as a draft * The draft state loads automatically when you reopen the entry * The browser does not display the standard “unsaved changes” warning **Note** If your internet connection drops before changes are synced, recent edits may not be saved. Confirm that the status indicator shows that changes are synced before leaving the page. ### Does a Draft Automatically Convert to a Version? No. [Drafts and Auto Save](/docs/content-managers/author-content/about-drafts-and-auto-save) creates and updates draft states only. A draft becomes a major version only when you explicitly click **Save** or **Publish**. Until then: * Changes remain in draft state * Entry Listing page displays a **Draft** pill ### What Happens During Network Delays or Sync Conflicts? [Drafts and Auto Save](/docs/content-managers/author-content/about-drafts-and-auto-save) uses a debounce-based mechanism. Changes sync automatically after you pause typing. If a network delay occurs: * The status indicator shows that changes are syncing * Editing may pause and become temporarily unavailable, if connectivity is lost If another user edits the same entry: * Fields they are editing become locked for you * You can view updates shortly after they are saved * You cannot modify a field that is currently locked **Warning** You cannot edit a field while another user is actively editing it. The field becomes available after the lock is released. ### Can I Compare Draft Changes? Yes. You can compare: * Minor draft updates (auto-saved changes) * Major saved versions Compare helps you: * Review collaborative edits * Validate changes before saving * Identify differences between draft and major versions **Note** Draft versions are retained only for the **five most recent major versions** of an entry. When newer major versions are created, draft updates associated with older major versions are automatically removed. As a result, only recent drafts appear in the version comparison panel. ### What If Another Version Is Newer Than My Draft? If another user saves or publishes a newer version while you are editing: * A notification appears * Editing may be temporarily restricted * You must compare your draft with the newer version before saving to avoid overwriting changes **Note** Always compare your draft with the latest version before saving if you receive a notification about a newer version. ### Do Drafts and Auto Save Create Too Many Versions? No. Minor updates are grouped in draft logs. Only explicit **Save** or **Publish** actions create major versions. This reduces unnecessary version creation while maintaining a clear version history. ### Can Multiple Users Edit the Same Entry at the Same Time? Yes, with field-level locking. * Each field locks individually when edited * Other users can edit different unlocked fields * Structural actions in container fields may be restricted if nested fields are locked This allows collaboration while preventing direct editing conflicts. ## Entries FAQs ### How can I preview my entry before publishing? Contentstack offers [Live Preview](/docs/content-managers/live-preview/about-live-preview/) functionality, enabling you to review your entry content across various channels before saving or publishing it on your live website. This feature allows you to edit an entry and observe content changes simultaneously in real-time. ### If I have deleted an entry that has currently been published to an environment, how will this action impact the entry? When you delete an entry that has been published, that entry will get unpublished. This means that the entry will cease to display on your web/mobile property. ### Is the entry UID unique per stack? Or is it unique to a content type? Entry UID is unique per stack. ### How is versioning of entries handled? Every time you save an entry with changes, Contentstack creates a new version of the entry. Users can view all the versions and compare any two versions of an entry at a time. If you wish to switch back to a previous version, you can simply click the Version drop-down of your entry's page and 'View' the version or 'Compare' an earlier version with the current version from the list. If you wish to make any previous version as the latest version of the entry, just select the required previous version and click on 'Save'. ### How do I know if an entry sent for publishing is actually published? The '[Publish Queue](/docs/content-managers/publish-content/view-publish-status-of-entries-assets-in-publish-queue)' section shows the list of all the items sent for publishing, along with its current publish status (published/pending/failed). ### I am wondering why the status of the entries in my Publish Queue is marked as 'Pending'? When I attempt to retrieve entries using the Content Delivery API I get an empty array. First, you need to check whether the ‘Deploy Content to Server’ option is enabled for the environment to which the entry is published. Then, the latest version of the contentstack-express server needs to be installed on your system. Until then, the status of entries shall be displayed as pending. ### Can we bulk publish multiple entries at once? Yes. Currently, you can [bulk publish multiple entries](/docs/content-managers/author-content/bulk-publish-entries). Check out the [CLI guide](/docs/developers/web-framework/contentstack-express-command-line-utility#publish) and [Publish an Entry](/docs/content-managers/working-with-entries/publish-an-entry) sections to know more. You can also bulk publish multiple entries with nested references at once. Check out our [Bulk Publish Entries with Nested References](/docs/content-managers/author-content/bulk-publish-entries/#bulk-publish-entries-with-nested-references) documentation to know more. ### Can I publish nested references while publishing a single entry? Yes, you can publish all nested references up to 5 levels of depth by publishing a single parent entry. Check out our [Publish Entries with Nested References](/docs/content-managers/author-content/publish-an-entry/#publish-entries-with-nested-references) documentation to know more. ### I am trying to create a new entry using the API and I am getting the following permissions error: { "error_message": "Access denied. You have insufficient permissions to perform this operation.", "error_code": 162 }. What could be the problem? To create entries in a stack, you need to be either the [owner of the stack](/docs/developers/invite-users-and-assign-roles/types-of-roles#owner) or you need to be assigned a role that contains write access to the stack. If you are not the owner of the stack, you need to acquire write access to your role from the owner of the stack. ### I have published entries but have not been able to find information on how to change the status in the Publish Queue. When you publish an entry, the system automatically puts it in the queue for publishing. The ‘Publish Queue’ section shows the list of all the items sent for publishing, along with their current status. You cannot manually change the status of an entry in the Publish Queue. ### Does Contentstack provide auto-save feature? If, by chance, I leave the page while in the midst of creating an entry or content type, will Contentstack save the data? Contentstack does not support the auto-save feature, and so, unsaved data will be lost if not saved manually by the user. To avoid such inconveniences, always make sure you save the data before navigating away from the page. ### If I have published a set of entries of Content Type ‘ABC’ on an environment (let’s say, staging), and then made some changes to the structure of this content type, will this impact the entries that I had published on ‘staging’? No. The published entries in this case will not be affected. It will only be affected if you republish the entries on ‘staging’ after making changes to the content type ABC. Note that making changes to an existing content type (having entries) may cause the [entries](/docs/content-managers/working-with-entries/about-entries) to lose data in Contentstack, but not on the published [environment](/docs/developers/set-up-environments/about-environments). ## Entry Comments FAQs ### Which users or roles can use the entry comments feature? Users or roles with "read" access to a specific content type or entry can access the entry comments feature. For more information, refer to the [Mention Users or Roles in a Comment](https://www.contentstack.com/docs/content-managers/author-content/mention-users-or-roles-in-a-comment) document. ### Can we set up a webhook to trigger based on entry comments? No, webhooks cannot currently be triggered by entry comments. ### I have comments on a field that was later deleted. Can I still access those comments? If you delete a field with associated comments, both the field and its comments will no longer appear in the entry editor. The discussion automatically resolves and moves to the **Resolved** section in the **Discussions** tab. You can access these details anytime through the Discussions tab in the right navigation panel. For more information, refer to the [Entry Comments](https://www.contentstack.com/docs/content-managers/author-content/about-entry-comments/) document. ### Can I add comments to a Global field or Group field as a whole? No, comments can only be added to the subfields of "Group" and "Global Fields", but not to the parent field as a whole. For more information, refer to the [Add a Comment](https://www.contentstack.com/docs/content-managers/author-content/add-a-comment) document. ### I am unable to add comments to a Global field in my entry marked as “Multiple”. How can I resolve this? To add comments to the subfields of a "Group", "Modular Blocks", or "Global" field marked as "Multiple," you must first enter data in the fields and save the entry. After saving, you can start adding comments to the subfields. For more information, refer to the [Add a Comment](https://www.contentstack.com/docs/content-managers/author-content/add-a-comment) document. ### Can I add comments to a Modular Blocks field as a whole? No, comments can only be added to the fields inside each block of a "Modular Blocks" field, not to the parent "Modular Blocks" field as a whole. For more information, refer to the [Add a Comment](https://www.contentstack.com/docs/content-managers/author-content/add-a-comment) document. ### Can I have more than one active discussion in the same field? No, only one active discussion is allowed per field. However, an entry can have multiple open discussions across different fields. For more information, refer to the [About Discussions](https://www.contentstack.com/docs/content-managers/author-content/about-discussions) document. ### Can I reopen a resolved discussion? Yes, you can reopen a resolved discussion if there is no active discussion on the field it was originally linked to. For more information, refer to the [Reopen a Discussion](https://www.contentstack.com/docs/content-managers/author-content/reopen-a-discussion) document. ### Can I have separate discussions for entries present in the master locale and other localized versions of the entry? Yes, discussions can be field-specific for each localized version of an entry. However, the "Comments" feature is not available for unlocalized entries or older versions. For more information, refer to the [About Discussions](https://www.contentstack.com/docs/content-managers/author-content/about-discussions) document. ### Can I track the history of changes to a comment? No, changes or edits made to comments are not tracked. Once submitted, comments are saved as-is. ### Are comments visible in exported entries? No, comments and discussions are not included in the exported entry data. ### Will users be notified when a comment is added? Yes, tagged users receive email and [in-app notifications](https://www.contentstack.com/docs/manage-notifications). ### Is it possible to tag external users or teams in a comment? No, only users with access to the content type or entry can be tagged or notified. For more information, refer to the [Mention Users or Roles in a Comment](https://www.contentstack.com/docs/content-managers/author-content/mention-users-or-roles-in-a-comment) document. ### Do comments in one locale carry over to other locales? No, comments are specific to the field in the locale they are added to and do not carry over to other localized versions. ### If I change the master locale entry, will it impact comments in localized versions? No, changes to the master locale entry do not affect the comments or discussions in localized versions. ### Can I disable the comments feature for specific fields or entries? No, currently, the comments feature cannot be disabled for specific fields or entries. ### What happens to old discussions after they are resolved? Resolved discussions remain accessible in the **Resolved** section of the **Discussions** tab for future reference. For more information, refer to the [View Discussions Timeline](https://www.contentstack.com/docs/content-managers/author-content/view-discussions-timeline) document. ### What happens to comments if an entry is deleted? If an entry is deleted, all associated comments and discussions are permanently removed. While you can restore the entry from the Trash, the previous discussions cannot be recovered. For more information, refer to the [Edit or Delete a Comment](https://www.contentstack.com/docs/content-managers/author-content/edit-or-delete-a-comment) document. ## Entry Variants FAQs ### What are Entry Variants in Contentstack? Entry Variants allow you to create different versions of an entry based on specific criteria, such as different languages, regions, or user preferences. This feature helps manage diverse content within the same entry structure. Learn more about [Entry Variants](/docs/content-managers/entry-variants/about-entry-variants). ### How do I create Entry Variants? To create Entry Variants, go to the **Entries** section within your stack. When creating or editing an entry, you can create entry variants by selecting a variant from the “Variants” dropdown and updating the content specific to the selected variant. Learn more about [creating entry variants](/docs/content-managers/entry-variants/create-an-entry-variant). ### Can I use Entry Variants with all content types? Yes, you can create Entry Variants for all content type entries available in your stack as long as your content type is linked to variant groups. Learn to [manage variant groups](/docs/developers/variants/manage-variant-groups). ### How do I switch between Entry Variants? You can switch between Entry Variants using the “Variants” dropdown menu available in the entry editor. Select the desired variant to view or edit it. ### Are there any limitations when using Entry Variants? Yes, some limitations include the Taxonomy not supporting the Variants feature and that you cannot create, delete, or edit the title and description of variant groups or variants within the stack. **Note:** Variant Groups correspond to the [experiences](/docs/personalize/about-experiences) created within your Personalize projects. Learn more about the [limitations for entry variants](/docs/content-managers/entry-variants/limitations-for-entry-variants). ### Can I localize Entry Variants? No, you cannot directly localize an entry variant. However, you can create an entry variant specifically for a localized language. To do this, select a localized entry first, and then create an entry variant for that language. This allows you to manage content variations for different languages. ### How do I manage versions of Entry Variants? Managing versions of Entry Variants can be more complex than standard entries. Use the version history feature to track changes and revert to previous versions as needed. Learn more about [managing versions of entry variants](/docs/content-managers/entry-variants/manage-versions-of-entry-variants). ### Can I publish entry variants independently? Yes, each entry variant can be published independently, allowing you to control which variants are live at any given time. Learn more about [publishing entry variants](/docs/content-managers/entry-variants/publish-an-entry-variant). ### How does publishing affect other variants of the same entry? Publishing one entry variant does not impact the published status of other entry variants for the same entry. Each entry variant's status is managed separately. Learn more about [publishing entry variants](/docs/content-managers/entry-variants/publish-an-entry-variant). ### How does language-specific publishing work for entry variants? You can publish entry variants in all the available languages of your stack. However, an entry variant can only be created for a language if the base entry is localized for that particular language. Learn more about [how publishing works with entry variants](/docs/content-managers/entry-variants/understanding-how-publishing-works-with-entry-variants). ### Can I unpublish an entry variant? Yes, unpublishing an entry variant will remove it from public view, while other published entry variants of the same entry remain unaffected. Learn more about [unpublishing entry variants](/docs/developers/variants/manage-variant-groups#unpublishing). ### Can I publish all entry variants at once? Yes, you can select entry variants from the entries list page and bulk publish them. Learn more about [how publishing works with entry variants](/docs/content-managers/entry-variants/understanding-how-publishing-works-with-entry-variants). ## Environments FAQs ### What is an environment in Contentstack, and why do I need one? An [environment](/docs/developers/set-up-environments/about-environments) in Contentstack is a specific publishing channel for your content. It helps you manage and preview your content effectively at different stages, such as development, staging, or production, before making it available to the public. This ensures content quality, reduced errors, and a seamless user experience. ### Can I use multiple environments within a single stack? Yes, you can create and manage multiple environments within a single stack. You can also create custom channels for specific needs (e.g., mobile apps, social media) using [Automate](/docs/developers/automation-hub-guides/about-automation-hub) or [Webhooks](/docs/developers/set-up-webhooks/about-webhooks). ### Is it possible to publish content simultaneously to multiple environments? Yes, you can [publish](/docs/content-managers/author-content/publish-an-entry) content simultaneously to multiple environments, such as **development**, **staging**, and **production**. This simplifies your workflow and ensures content consistency across environments. ### Can I create environments for mobile applications or social media platforms? Yes, Contentstack allows you to create dedicated environments tailored specifically for **mobile apps**, **social media**, or other custom channels using [Automate](/docs/developers/automation-hub-guides/about-automation-hub) or [Webhooks](/docs/developers/set-up-webhooks/about-webhooks). ### Who has permission to create, edit, or delete environments in Contentstack? Only the stack [Admin](/docs/developers/invite-users-and-assign-roles/types-of-roles#admin) and [Developer](/docs/developers/invite-users-and-assign-roles/types-of-roles#developer) can [create](/docs/developers/set-up-environments/add-an-environment), [edit](/docs/developers/set-up-environments/edit-an-environment), or [delete](/docs/developers/set-up-environments/delete-an-environment) an environment. ### What happens if I delete an environment that already has published content? If you [delete an environment](/docs/developers/set-up-environments/delete-an-environment) with published content, the associated [entries](/docs/content-managers/author-content/about-entries) and [assets](/docs/content-managers/author-content/about-assets) remain in Contentstack but become inaccessible via that environment. [Delivery tokens](/docs/developers/create-tokens/about-delivery-tokens) linked to the deleted environment are invalidated, preventing content retrieval through APIs. **Warning:** This action is permanent, and you cannot restore a deleted environment. ### How can I automate content deployments to multiple environments simultaneously? You can automate content deployments to multiple environments simultaneously by configuring [Webhooks](/docs/developers/set-up-webhooks/about-webhooks) or using [Automate](/docs/developers/automation-hub-guides/about-automation-hub). Webhooks allow you to trigger automatic deployments to multiple servers or services whenever you publish or update content. Automate provides visual workflows to schedule, coordinate, and manage deployments across multiple environments, ensuring consistency. ### Can different environments have different base URLs? Yes, each environment can have a different **Base URL**. This allows you to publish content to distinct locations, such as separate URLs for **development**, **staging**, and **production**, based on your deployment workflow. ### Is it possible to use the same environment for multiple stacks? No, an environment is specific to a single [stack](/docs/developers/set-up-stack/about-stack) and cannot be shared across multiple stacks. Each stack requires its own set of environments to manage and deploy content independently. ### How do environments interact with multilingual content setups? Environments support multilingual content by allowing language-specific **Base URLs**. You can set different URLs per environment for each [language](/docs/developers/multilingual-content/about-languages), enabling content to be published and managed effectively across multiple languages and regions. ### While setting up an environment, why do you ask for the base URL? The **Base URL** is the consistent part of the destination’s web address. It helps Contentstack identify the destination to which you will publish the content, for example, www.yourdomain.com. ### Should I enter a base URL while setting up an environment for my mobile application? No, you do not need to enter the **Base URL** while setting up the environment for your mobile application. This is because the apps fetch content directly from Contentstack via APIs. ### Are environments shared across all branches in Contentstack? Yes, environments are [global modules](/docs/developers/branches/global-modules) available across all [branches](/docs/developers/branches/about-branches) of your [stack](/docs/developers/set-up-stack/about-stack). Any environment created in the main branch will be accessible in all other branches. ## Experience Extensions FAQs ### How do you sandbox an extension iframe? To separate an extension from Contentstack, we make use of the [HTML5 sandbox attribute](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe#attr-sandbox) on the iframe. And, the following sandbox flags are enabled: * allow-scripts: This flag re-enables an extension to run JavaScript in its own sandbox * allow-popups: Use this flag to enable your extension to open pop-ups. * allow-popups-to-escape-sandbox: This flag allows the sandboxed document to open new windows without imposing any sandbox-specific restrictions on them. **Note:** For external hosting of extensions, the allow-same-origin option will be enabled, where the origin refers to the domain where you've hosted the extensions. Also, ensure that the response header has the exact origin URL passed in the request header. For Contentstack-hosted extensions, the iframe's origin will be null as we don't enable the allow-same-origin flag. ### Is hosting extensions on HTTPS a mandatory process? Yes, it is mandatory to host your extensions on HTTPS as we do not allow users to reference non-HTTPS URLs (i.e., http://) with the exception of Localhost URLs (http://localhost) which are used for development purposes. If you plan to serve your extension from localhost, block mixed content protection in [Chrome](https://support.google.com/chrome/answer/1342714) and [Firefox](https://support.mozilla.org/en-US/kb/mixed-content-blocking-firefox). ### Do we need to make use of the CORS mechanism? Since an extension is run in a sandboxed iframe, it receives the origin null. Because of this reason, custom web fonts do not work as expected. In order to overcome this, you need to configure your servers to send the headers: Access-Control-Allow-Origin null or Access-Control-Allow-Origin ### Can I customize Contentstack’s field appearance? Yes, but only of the fields that you create using Contentstack’s UI [Extensions](/docs/developers/about-experience-extensions). You cannot customize the appearance of Contentstack’s default fields ### How can I install an Extension? There are two ways to install Extensions in Contentstack: * Via [Contentstack UI](/docs/developers/developer-hub/about-ui-locations). * Using [Extensions Content Management APIs](/docs/developers/apis/content-management-api#extensions) **Note:** Extensions are going to be deprecated soon. We encourage you to visit our [Marketplace](/docs/developers/marketplace-apps) to get a complete list of available apps. ### What are common use cases for Extensions? * [Color picker](/docs/developers/create-custom-fields/use-prebuilt-custom-fields/color-picker) * [YouTube video selector](/docs/developers/create-custom-fields/youtube) * [Key-value pair fields](/docs/developers/create-custom-fields/use-prebuilt-custom-fields/key-value-field) * Product catalog viewer * [Salesforce](/docs/developers/create-custom-widgets/salesforce-einstein)/[Marketo](/docs/developers/create-custom-fields/marketo-forms) data fetcher For more experience use cases, read [All Contentstack Experience Extensions](/docs/developers/all-contentstack-experience-extensions) document. The possibilities are endless. You can create a custom field and/or integrate the field with third-party apps. ### Are there any naming conventions to be followed when creating extensions? No, there are no validation rules to be followed when choosing extension names. But do try to keep it short because long names can break the layout. ### When creating a particular content type, can I use multiple Extension fields? If yes, is there any limitation to it? Yes, you can use multiple [extensions](/docs/developers/about-experience-extensions) in a [content type](/docs/developers/create-content-types/about-content-types). There are no limitations pertaining to using Extension fields. However, for content types, we have a field limitation of 100, which is applicable to Extension fields too. ### Are there any limitations to using extensions in general? Yes, there are certain limitations to using extensions. They are as follows: * **Size:** The maximum size of an extension is **500 KB** * **Title:** The title of an extension cannot exceed **256** characters * **Stack limit:** At most **50** extensions can be installed in a stack. * **Config file size:** The size limit of an extension’s configuration file is **10 KB** * **JSON data type size:** The maximum size limit of the JSON Data Type is **10 KB** * **Browser-support:** Internally hosted extensions are not supported on Internet Explorer and Microsoft Edge as they lack support for the